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  • Program TV-7D/U?

    From Jerome Kaidor@21:1/5 to All on Mon Mar 6 13:44:11 2023
    Hello!

    I haven't messed with tubes in years, but here I am... I was resurrecting a
    Heathkit SB-610 ham radio station monitor. Everything working except the two-tone generator. This is a pair of audio oscillators that generate audio, one at 1500Hz, the other at 1800. Or - well - they're supposed to. They actually don't.

    I popped the tube and measured all the resistances; they're all a little high. A weakness of traditional carbon composition resistors. I have ordered a box of 1/2W 1% metal film resistors from Amazon.

    That leaves the tube. It's a 6J11 "dual sharp cutoff pentode". How to test it? It might not be necessary. The thing might just spring to life with proper
    resistors. Or it might not.

    The only tube testers I have are 3 TV7D/U's that I bought at the flea market back in the 90's. Paid $100 for one of them, $20 each for the other two. I am truly amazed at the prices these things are fetching on Ebay.

    This 6J11 is way too new for the TV7s. But... a tube is a tube, right?

    I have a couple of Novatron->octal adapters that I bought in 1993 from Dan Nelson. The 6J11 has 12 pins - naturally, four of them are not connected by the adapter.

    Just for yuks - I could do something with an octal plug and some clip leads.

    Is there any info out there on adapting a TV7 to tubes at are not in its databook?

    I found a PDF of the TV7 manual on the Net, and after much printing, cutting, and taping, I have a complete schematic. ( Not the "D" version, but it should be similar enough... )

    It's daunting. Lots of wires & switches. Luckily - as far as I know - I don't need to troubleshoot the tube testers. I just need to figure out the switch positions to connect the tube elements.

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  • From Peter Wieck@21:1/5 to All on Tue Mar 7 06:14:48 2023
    chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/http://www.r-type.org/pdfs/6j11.pdf

    Is your pinout. The filament is 6.3 V, AC or DC, at 0.8 amps. This is a dual-pentode as you already stated.

    With some finagling, and the data on the sheet, it would seem feasible to test each pentode separately, meaning you would need to connect only seven pins (5 + heater) at a time.
    As it happens Compactrons are remarkably resilient tubes, and short of physical damage and/or an open filament, it should be OK. Question: Does it light up?

    Peter Wieck
    Melrose Park, PA

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    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Tater@21:1/5 to jkaidor@gmail.com on Tue Mar 7 10:33:34 2023
    I have a set of 4 manuals for the TV-7/U in PDF form which I'd be glad
    to e-mail to you if you need them. There is the test data booklet,
    the operator's manual, parts list, and depot maintenance manual.
    They all include the D model as well.

    Jerry

    On Mon, 6 Mar 2023 13:44:11 -0800 (PST), Jerome Kaidor
    <jkaidor@gmail.com> wrote:

    Hello!

    I haven't messed with tubes in years, but here I am... I was resurrecting a
    Heathkit SB-610 ham radio station monitor. Everything working except the two-tone generator. This is a pair of audio oscillators that generate audio, one at 1500Hz, the other at 1800. Or - well - they're supposed to. They actually don't.

    I popped the tube and measured all the resistances; they're all a little high. A weakness of traditional carbon composition resistors. I have ordered a box of 1/2W 1% metal film resistors from Amazon.

    That leaves the tube. It's a 6J11 "dual sharp cutoff pentode". How to test it? It might not be necessary. The thing might just spring to life with proper
    resistors. Or it might not.

    The only tube testers I have are 3 TV7D/U's that I bought at the flea market back in the 90's. Paid $100 for one of them, $20 each for the other two. I am truly amazed at the prices these things are fetching on Ebay.

    This 6J11 is way too new for the TV7s. But... a tube is a tube, right?

    I have a couple of Novatron->octal adapters that I bought in 1993 from Dan Nelson. The 6J11 has 12 pins - naturally, four of them are not connected by the adapter.

    Just for yuks - I could do something with an octal plug and some clip leads.

    Is there any info out there on adapting a TV7 to tubes at are not in its databook?

    I found a PDF of the TV7 manual on the Net, and after much printing, cutting, and taping, I have a complete schematic. ( Not the "D" version, but it should be similar enough... )

    It's daunting. Lots of wires & switches. Luckily - as far as I know - I don't need to troubleshoot the tube testers. I just need to figure out the switch positions to connect the tube elements.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jerome Kaidor@21:1/5 to All on Thu Mar 9 15:07:53 2023
    Well.

    I replaced all the resistors in that two-tone oscillator - and it sprang to life! Works fine on both frequencies now. I suspect that the cathode resistors had gone up enough in value to put the operating point out of the "can oscillate" range.
    Maybe in combination with the plate load & screen resistors going up also. Took the better part of a day, because I carefully unsoldered and removed all the parts. Then cleaned the tube socket off with alcohol & cleaned the chassis around it. Then
    hand-selected resistors closest to the book values from my Amazon kit ( which according to my Fluke multimeter, are NOT 1% resistors. Maybe 5% ).

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    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Peter Wieck@21:1/5 to All on Fri Mar 10 05:08:03 2023
    Thank you for letting us know. Few do.

    Peter Wieck
    Melrose Park, PA

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